The openstack server create command provides a --nic argument that specifies the network or port to be attached to the instance.

Users can specify a network identified by the network's ID by using the net-id key:

--nic net-id=<Network ID> 

In the preceding example, Nova interfaces with the Neutron API to create a port using the network ID provided by the user. Neutron then returns details of the port back to Nova for use by the instance. Users can request a specific unused IPv4 or IPv6 address using the v4-fixed-ip and v6-fixed-ip keys, respectively, as shown here:

--nic net-id=<Network ID>,v4-fixed-ip=<ipv4 address>
--nic net-id=<Network ID>,v6-fixed-ip=<ipv6 address>